Problem: How many paths are there from $A$ to $B$, if every step must be up or to the right?[asy]size(4cm,4cm);int w=6;int h=5;int i;pen p=fontsize(9);for (i=0; i<h; ++i){draw((0,i) -- (w-1,i));}for (i=0; i<w; ++i){draw((i, 0)--(i,h-1));}label("$A$", (0,0), SW, p);label("$B$", (w-1,h-1), NE, p);[/asy]
There are 5 steps to the right, and 4 steps up.  These 9 steps can be made in any order, so we can choose 4 of the 9 steps to be "up" in $\binom{9}{4} = \boxed{126}$ ways.